Cooling means for electric metal-working transformers



. J. H. GRAVELL. COOLING MEANS FOR ELEQTRlQ-METAL WORKING TRANSFORMERS.-

APPLICATION men on. 4. 1s19.

- 1,3 2,905. r mnmunezs, 1921.

Jams 19 rffvel/ v 3511/! Queen W43 weldin UNITED STATES PATENT OFFICE.

JAMES H. GBAVELL, OF ELKINS PARK, PENNSYLVANIA, ASSIGN'OB T0 THOMS ONELECTRIC WELDING COMPANY, OF BOSTON, MASSACHUSETTS, A. CORPORA- v TIONOF MASSACHUSETTS.

COQLING FOR ELECTRIC METAL-WORKING TRANSFORMERS.

Specification of Letters Patent. Patented June 28, 1921.

Application filed October 4, 1919. Serial No. 328,544.

To all whom it may concern Be it known that 1, JAMES H. GnAvnLL, acitizen of the United States, and a resident of Elkins Park, in thecounty of Montgomery and State of Pennsylvania, have invented certainnew and useful Improvements in Cooling Means for Electric Metal-WorkingTransformers, of which the following is a specification.

This invention relates to the cooling electric coils of transformers forelectric metal working apparatus or of other apparatus. The invention isherein described as applied to the welding transformer although it maybe used in the coils of transformers for other metal working operationsor of otherthe cooloperation of the coil and the transformer or otherapparatus of which it forms a part and to reduce the space occupiedthereby, thus reducing the cost of manufacture, the weight and its selfinductance, while at the same time permitting the use of a conductingfluid and a cooling medium without objectionable difference of potentialexisting at the ends of the fluid stream.

It is well known in the design of the transformer that the resistance ofthe primary windings in itself is of little importance and may be variedover a long range without affecting the practical current output. It is,however, of high importance that the apparatus remain ieasona ly cold sothat the insulation is not injured and it therefore becomes necessary tomake the primary conductors of large cross-section not to lessen theresistance but to reduce their heating.

According to the present invention the primary winding can have anydesired crosssection on a maximum lcsistance and no consideration of theradiating surface is necessary, while moreover the presence of theconducting cooling medium in contact with the coil introduces nodifficulty arising from a difference of potential between the inlet andoutlet ends of the stream of cooling fluid.

In order to accomplish the objects of this core A. The source of currentpassed through the tubular primary or other coil, thus maintaining it ata relatively low temperature, but the coil is so constructed and thefluid is so circulated through the same that the electrical potential ofthe fluid at the two ends of the tube will be the same. Any othercooling medium such as alcohol or air might be passed through theconductors but I prefer to use water for obvious reasons, such ascheapness, ease of handling, &c.

The invention consists in the construction of coil and manner ofcirculating the cooling fluid therethrough as hereinafter moreparticularly described and then set forth in the claims.

In the accompanying drawings the invention is diagrammaticallyillustrated to show the principle thereof in the simplest manner, itbeing understood that the construction shown is for the purpose ofillustration only.

a The drawing shows in elevation a coil so constructed that my presentinvention may be carried into efiect.

With a single tubular coil in which'the coolin medium and the currentare circulated in one direction only there is a difference of potentialbetween the inflowing water and the outflowing water that in some casesmight cause serious trouble due to short 'circuiting the current,particularly in the case when the coilis a primary coil.

To overcome this disadvantage, I provide the construction as shown inthe drawings. In this'case the conductor consists of two tubes B and Bwound in electrical arallel on the is connected so as to branch throughthe two coils flowing from theline terminal E to the two tubularterminals B and B then through the two coils to the points D and D andto the other line terminal E The two tubular coil ends D and D" areconnected together as at D so that the cooling medium can flow from oneto the other as shown, making the two coils one continuous tube or pipefor the conduct ends F and F It will be observed that although theelectric current flows in parallel through the two windings, the coolingmedium flows through the two windings in serles. V

When my invention is employed with a transformer the primary 0011 may beof small dimensions without danger. of overheating. Owing to thesmallness of the primary, the secondary shown at G may be placed muchnearer to the core than in the old construction of the primary which, incase a continuous or closed core is used, enables the total length ofcore to be reduced. This has the advantage of reducing the selfinductance of the transformer and reducing the eddy current andhysteresis losses. These factors work tothe great advantage of currentoutput of the secondary which is so desirable in metal workingtransformers.

The means of insulating the various convolutions of the primary is notshown, as this is well understood in the art.

The invention claimed is 1. An electric coil having two windings ofhollow tubing connected to permit the cooling medium to flow throughthem in series and having electrical connections to cause electriccurrent to flow through them in parallel.

2. An electric conductor made of two sections or lengths of hollowtubing connected to permit the cooling medium to flow through them inseries and having electrical connections to cause electric current toflow through them in parallel.

3. A transformer having two windings of hollow tubing connected topermit the cooling medium to flow through them in series and havingelectrical connections to cause electric current to flow through them inparallel.

Signed at New York, in the county of New York and State of New York,this 1st day of October, A. D. 1919.

JAMES H. GRAVELL.

Witnesses:

F. B. TOWNSEND, IRENE LEFKowITz.

